Conservatism of Late Pennsylvanian vegetational patterns during short-term cyclic and long-term directional environmental change, western equatorial Pangea
Neil J. Tabor, Charles M. Romanchock, Cynthia V. Looy, Carol L. Hotton, William A. Dimichele, Dan S. Chaney, 2013. "Conservatism of Late Pennsylvanian vegetational patterns during short-term cyclic and long-term directional environmental change, western equatorial Pangea", Palaeozoic Climate Cycles: Their Evolutionary and Sedimentological Impact, A. Gąsiewicz, M. Słowakiewicz
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Patterns of plant distribution by palaeoenvironment were examined across the Pennsylvanian–Permian transition in North–Central Texas. Stratigraphically recurrent packages of distinct lithofacies, representing different habitats, contain qualitatively and quantitatively different macrofloras and microfloras. The species pools demonstrate niche conservatism, remaining closely tied to specific habitats, during both short-term cyclic environmental change and a long-term trend of increasing aridity. The deposits examined principally comprise the terrestrial Markley and its approximate marine equivalent, the Harpersville Formation and parts of lower Archer City Formation. Fossiliferous deposits are lens-like, likely representing fill sequences of channels formed during abandonment phases. Palaeosols, represented by blocky mudstones, comprise a large fraction of the deposits. They suggest progressive climate change from minimally seasonal humid to seasonal subhumid to seasonal dry subhumid. Five lithofacies yielded plants: kaolinite-dominated siltstone, organic shale, mudstone beds within organic shale, coarsening upward mudstone–sandstone interbeds and channel sandstone. Both macro- and microflora were examined. Lithofacies proved compositionally distinct, with different patterns of dominance diversity. Organic shales (swamp deposits), mudstone partings (swamp drainages) and coarsening upward mudstone–sandstone interbeds (floodplains) typically contain Pennsylvanian wetland vegetation. Kaolinite-dominated siltstones and (to the extent known) sandstones contain taxa indicative of seasonally dry substrates. Some kaolinite-dominated siltstones and organic shales/coals yielded palynomorphs. Microfloras are more diverse, with greater wetland–dryland overlap than macrofloras. It appears that these two floras were coexistent at times on the regional landscape.
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Palaeozoic Climate Cycles: Their Evolutionary and Sedimentological Impact
This volume presents results of a variety of case studies documenting the Late Palaeozoic climate changes and cyclicity of deposition. The collected papers cover many aspects related to palaeoenvironmental analysis with sedimentological, stratigraphic, palaeobiological, geochemical, and palaeomagnetic studies of the fossil record around the Late Palaeozoic Ice Age and soon after. They span a stratigraphic interval from Carboniferous to Permian–Triassic transition around the world.
This book comprising results for a range of disciplines, is a valuable source for not only researchers who are actively working on specific aspects of the Late Palaeozoic and looking for an up-to-date reference on this inhospitable time in the Earth’s history. It is also of interest to climate modellers and the wider scientific community with an interest in the latest research on the decline of the Palaeozoic World.